breaking news overnight. Several explosions in t mobile, alabama, area, not far from downtown mobile, where two fuel barges were being cleaned. You can see the massive fireball here. Serious injuries are now being reported. Abc's john muller has been following the developments all night long. Reporter: A massive fireball, lighting up the night sky over mobile, alabama. So bright, so loud, one witness thought it was a plane dropping bombs. The coast guard, joining local firefighters, rushing to the waterfront. We have a fuel barge on fire. Fire one, we've had an explosion. Reporter: It wasn't one explosion or two. But seven. All happening as two barges were being cleaned after carrying liquid natural gasoline. The situation so unstable, crews decided to let the fire burn itself out. Imposing a one-mile safety zone around the area to keep people out. If we can determine -- we're not going to somebody hurt here for no reason. Reporter: Nearby, the carnival cruise liner "triumph," being repaired after the disaster in the gulf in february. Hundreds of crew members forced to evacuate. Back at the barges, three workers are critically injured as investigators try to get to the bottom of what happened here. For "good morning america," john muller, abc news.

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